Photography in natural colors



Dec. 25, 1934. H. E. IVES 1,985,731

PHOTOGRAPHY IN NATURAL COLORS Original Filed March 20, 1930 2Sheets-Sheet 1 FIG. I

I l l l 1 I l l l SECTION 3'3 FIG. 2C

INVENTOR- H. E. VES

ATTORNEY Dec. 25, 1934. H. E. IVES 1,985,731

PHOTOGRAPHY IN NATURAL COLORS Original Filed March 20, .1950 2 Sheets-Sheet 2 FIG. 3

2 92 b & &

FIG. 60

IIVVENTOR H. E. lVL-S A T TORNE V Patented Dec. 25, 1934 PATENT OFFICE1,985,731 PHOTOGRAPHY m NATURAL coLons Herbert E. Ives. Montelair, N..L, minor to Bell Telephone Laboratories, Incorporated, New York, N. Y.,a corporation of New York Original application March 20, 1930, SerialNo.

Divided and this application July 31,,

1931, Serial No. 554,207

2 Claims.

This invention relates to photography and more particularly to methodsof and means for producing photographic effects in colors.

In a well known form of color photography a film with ridged lentic'ularelements on the surface opposite to the light sensitive emulsion isused. This film is exposed in a camera, the lens of which is providedwith three adjacent color filters such as are used in producingblack andwhite color records. The ridged surface faces the lens and thephotographic emulsion on the side of the film opposite the ridges isexposed to three juxtapositioned linear color record images for eachlenticular ridge. The exposed film dur ing development is reversed toform a positive which may be projected on a screen to produce an imagein natural colors by means of a projection lantern the lens of which isalso provided with three adjacent color filters. A limitation of thisprocess is that only one film is produced for projection.

An object of the present invention is to facilitate the production ofduplicate copies of such ridged film.

By way of illustration 2. limited number of embodiments of the inventionwill be described.

In one form of the invention a colored image is projected from theoriginal film upon a translucent screen. This image is thenrephotographed with a camera having its colored lens filters and ridgedfilm at an angle, preferably of 90 degrees, to the filters and film ofthe project= ing device in order to obviate moir or patterns inthecopiedfilm. However, it is simpler to dispense with the projection ofthe image on the screen, and to do away with the filters entirely.Therefore in the preferred form of the invention, two cameras ofsuitable focal length and aper-= ture of lenses are placed lens to lens.The film to be copied, that is the original, is placed in one camera asif for projection. The unexposed film for the copy is placed in theother camera as if for taking. The lenticular ridges of the copy filmare at an angle, preferably of 90 degrees to the ridges of the original.A special apertured diaphragm is located between the lenses taking,

the place of the usual color filters, the apertures consisting of threerectangles arranged along a diagonal, each rectangle corresponding towhat would be the overlapping portions of the same color sections of thefilters were such filters retained. The resultant copy in consequence ofthe large angle between the directions of the ridges in the original andcopying film, is free from moir or patterns. For the copying of mo tionpicture films the original film may have its lenticular ridges extendlengthwise of the film strip while the ridges of the copy aretransverse, the films moving through the copying apparatus in oppositedirections in parallel planes. To permit of the same kind of film beingused for both the original and copy, for example film with lenticularridges running lengthwise of the strip, the original and the copy may berun through the copying apparatus at right angles. When operating inthis way the film during the taking process is preferably run throughthe taking camera in a horizontal direction. With the usual form ofmotion picture film, each picture frame is longer transversely to thefilm strip, than lengthwise thereof. In order to facilitate copying whenboth the original and copy have ridges running in the same direction,the long dimensions of the frames of the original are arrangedlengthwise of the film strip so that the frames of the copy will be ofusual form. In another form of the invention the lenticular ridges areneither lengthwise nor transverse of the film but at an angle to theedge of the film strip, preferably at 45 degrees. The same type of filmis used for both the original and copy, and is run through the takingcamera and the original side of the copying apparatus in the samedirection, through the two sides of the copying apparatus in oppositedirections, and through the copy side of the copying apparatus and theprojectorin the same direction. In copying, the original and the copyhave the ridged surfaces of the films facing each other so that the linestructure on the copy due to the ridges of the original are at rightangles to the ridges of. the copy, thus obviating moir or interferencepatterns.

This application is a division of application Serial No. 437,341, filedMarch 20, 1930 and is directed to that form of the'inventlon in which acolored image is projected, upon a translucent screen andrephotographeol.

The invention will now be described more in detail having reference tothe accompanying drawings:

Fig. 1 illustrates a form ofthe invention in whichfrom the original filma colored image is f ace views of the colored tion in which the colorfilters and screen been discarded.

Figs. 2A and 2C are surface views of the orighave inal and Copy films,respectively, of Fig. 2.

Fig. 6 illustrates another form of the inven-' tion which is similar tothat of Fig. 2 but the lenticular ridges form an angle of 45 degreeswith the edges of the film.

Figs. 6A and 6C are surface views of the original and copy films,respectively, of Fig. 6.

Fig. 6B is a face view of the apertured diaphragm of Fig. 6.

Fig. 6D is a. face view of color filters for either the taking orprojection with the type of film shown in Fig. 6.

Like reference characters are used to represent identical elements inthe several figures.

This invention is a practicable system for copying ridged lenticularfilm. 'It is obvious that any attempt to copy a ridged film picture bycontact printing upon another ridged film is impracticable because ofthe difficulty of exact registration of one set of ridges on the other.If recourse is had to simple projection printing the same difficulty isencountered, while if the picture is projected in color to berephotographed with a camera and film like those used in making theoriginal, interference patterns or moir will occur between the lines ofthe projected picture and the film unless at the cost of good definitionthe projected picture is deliberately blurred until the lines disappear.

This diflioulty is overcome in the arrangement of Fig. 1. I

An original image bearing ridged lenticular film 5 is arranged to becopied on a similar type of film 6. The image of film 5 is projected incolor by means of lens 7 and color filter 8 on a translucent screen 9.This image on the screen 9 is then rephotographed through the colorfilter Why the lens 11 upon the copy film 6. The film 5 is illuminatedfrom the left hand side either by a diffusing plate or by an extendedlight source and condensing system similar to that used for projectionon a viewing screen of images from this type of film in well knownmanner. The color filter 8 comprises three sections R, G and B whichcorrespond to the primary colors red, green and blue used in the wellknown three-color process. The ridged film 5 is a well known type. Theimage thereon consists of sets of linear color records corresponding toblack and white color records of the primary colors. The function of thelenticular ridges is to direct the light rays from the 1 linear colorrecords through the corresponding color filter sections R, G and B toproperly color the various elemental portions of the image projected onscreen 9 by the lens '7. The horizontal lines in Fig. 1A represent theridges on the face of film 5, the size of the ridges being enlarged outof proportion to the other elements of the system for the purpose ofillustration. The image formed on the screen 9 has a line structure dueto the ridges on the film 5. This structure is represented by thehorizontal dotted lines in Fig. 1C. The color filter 10 has sections R,G, and B which may be identical with the sections R, G and B of colorfilter 8 exceptthat the long dimension is parallel to the ridges on thefilm 6 and, therefore, at right angles to the line structure of theimage on screen 9. The surface of film 6 facing the lens 11 carrieslenticular ridges such that the emulsion of film 6 is exposed to sets ofcolor record images corresponding to the colors of the image on thescreen 9. The full lines of Fig. 1E represent this ridged structurewhile the dotted lines of this figure represent the line structure inthe image on film 6 due to the line structure of the image on screen 9produced by the ridges on film 5. Since the ridges of film 6 are atright angles to the line structure in the image on this film nointerference patterns or moir are produced. The subject matter imaged onthe films 5 and 6 and the screen 9 is represented by the arrow in Figs.1A, 10 and 1E.

For further details regarding the type of film here employed, theproducing of images thereon, and the projection of colored imagestherefrom, reference is made to Patent No. 992,151 of R. Berthon issuedMay 16, 1911.

Referring now to Fig. 2, a simplified copying system is shown in whichthe screen 9 of Fig. 1 has been discarded and the color filters 8 and 10have been replaced by an apertured diaphragm 12. The original film 5 isimaged on the copy film 6 by the lenses 7 and 11 which are both focusedfor parallel light. The ridges of film 5 are located horizontally whilethose of film 6 are vertical. The diaphragm 12 has special apertures r,g and b whose function is to take the light from each set of horizontalstrip images of film 5 and distribute it to the proper set of verticalridges of film 6. There are clear apertures, each of a size which wouldcorrespond to the overlapping portions of the corresponding colorsections of filters 8 and 10 of Figs. 13 and 1D, were these filterssuperposed. Thus, light from a red elemental color record of film 5 isdirected by its lenticular ridge through the aperture 1 to acorresponding point of film 6 where the ridge at that point directs thelight to a point in the emulsion to form an image of the aperture r.Light from the other color records are correspondingly directed throughthe other apertures g and b. Figs. 2A and 20 show the images, linestructures and ridges in the same manner as Figs. 1A and 1E. If thedefinition is exquisite the resulting picture in film 6 shows a mesh offine lines at right angles of equal spacing in both directions whichimpair the sharpnessof the picture no more than the regular lines in onedirection-both are supposedly invisible at the proper viewing orprojecting distance.

The method of copying, employed in Fig. 2, is applicable without anycomplications (except an inversion of the image from left to right whichmay be offset by the use of a mirror in taking) if the process ofphotographic reversal is used on both the original and the copy. It isapplicable also in principle to making positive copies from unreversednegatives. When this is done it is desirable to fill in the spacesbetween the image strips in order to avoid dilution by white light.

This does not appear possible in the negative; in the positive it can besecured by using special diaphragms between the lenses 7 and 11. Onesuch diaphragm is shown in Fig. 2D. The clear apertures are the same asin Fig. 2B but the diaphragm 14 is made of translucent material such asground celluloid. This throws diffused light from all points exceptwhere the aperture is cut-through. This celluloid aperture is thenblackened in either horizontal direction from the clear apertures r, g

' and b parallel to the ridges of film so that the interspaces betweenthe line images on film 6 can be given any photographic action desireddepending upon the translucency of the celluloid. Another form ofaperture for blackening the interspaces is shown in Fig. 2E where theapertures n, 01 and D1 are of such length that their images fill thewhole space between the ridges of film 6. In this arrangement theapertures are also shown as quite narrow-in order to take light onlyfrom the centers of the negative strip images, which arrangementminimizes the effects of scattered light in the negative. In Fig. 2Fstill another type of diaphragm 15 is shown. In this form the aperturesn, 91 and in are the same shape as in dia-= phragm 13 of Fig. 2E butadditional elongated vertical slots 16 and 1'7 are provided to throwlight from all three images into the spaces between the successive setsof three strip images. These additional slots 16 and 1'7 can, ifdesired, be illuminated from the side to insure the necessary intensityof illumination.

This method of projection copying is also applicable to motion picturefilms. Figs. 3, 4 and 5 show the invention applied to such films. Ineach of these figures a indicates the original film to be copied, while17 indicates the copy film. In Fig. 3 the original film has the ridgesrunning longitudinally while the copy has the ridges runningtransversely. These films are adapted for use in the optical system ofFig. 2, film a taking the place of film 5 and film 1) taking the placeof film 6. Suitable mechanisms, of course, are required for moving thefilms in proper synchronism through the copying device for copying frameby frame.

In the arrangement of Fig. 4 the ridges on both the original a and copyI) films run lengthwise of the film. Such an original film may beproduced by turning the motion picture camera through 90 degrees on itsoptical axis. This type of film may also be used in the optical systemof Fig. 2. Because of the rectangular shape of the frames thisarrangement results in losing a portion of each frame, the final picturecontaining only the square which is common to the two rectangular frameswhen superposed in this way. Such a square frame is shown by the fulllines in Fig. 4b.

In Fig. 5 there is shown types of film which obviate this loss.The-taking film a is narrower and the regular frames are arranged withtheir long dimensions parallel to the edge of the film as shown in Fig5a. When this filmiscopied in the optical arrangement of Fig. 2 onstandard film the standard shape'of frame is obtained as shown in Fig.5b.

In Figs. 3 and 5 different-types of films are required for the originaland the copy. An arrangement is shown in Fig. 6 wherein the same type offilm is used for both the original and the copy. This arrangement issubstantially the same as that of Fig. 2 except for the type of filmemployed and the position of apertured diaphragm used between lenses '7and 11. In this arrangement the lenticular ridges on the film form anangle of approximately degrees with the edge of the film and thedirectional slope is the same on both the original film 60 and the copyfilm 61. The ridged surfaces of both films 60 and 61 face towardeachother. The apertured diaphragm 62 is similar to the diaphragm 12 of Fig.2 except that it is turned through an angle of 45 degrees. Frames 64 and65 of Figs. 6A and 60 show the inversion of the image which takes placedue to the lenses '7 and 11. It will be seen that k the line structurein the copy, shown by the dotted lines in frame 66 of Fig. 6C, due tothe ridged structure of the original, is unchanged in slope due to thelens inversion. As a consequence property of falling at an anglesufficient to avoid patterns when imaged and inverted in this way. Nochange is necessitated in the camera-and projector for using this typeof film except that the colored apertures in front of the taking andprojection lenses must stand at an angle as shown in Fig. 6D.

In each of these arrangements inversions take place which may becompensated by the use of mirrors as desired. Thus, a right to leftinversion may be compensated by a plain vertical mirror placed at asuitable angle to the optical axes of the optical system.

Suitable housings may be provided for the elements of the variousoptical systems described to exclude unwanted light and to properlycontrol the time of exposure of the copy films, such as films 6 and 61.

The term film, as used herein, denotes not only the celluloid film ofwell known kind, but also is intended to cover forms of emulsioncarrying material other than such celluloid film provided the ridgedlenticular elemental structure is retained.

The shape and size of the color filter sections may be varied to suitthe needs of any given equipment and in conformity with the emulsions,which are being used. The rectangular form of sections are shown in thedrawings merely for convenience. The shape of the clear apertures is ofcourse dependent upon the shape of the taking color filters and the typeof record desired on the copy film.

It is also to be noted that various forms of lenses may be used providedonly that they accomplish the primary function of lenses 7 and 11.Composite lenses for correcting for well known optical defects of simplelenses will usually be found preferable to simple lenses. Such lensesare well known to those skilled in this art.

- Mechanism for moving motion picture films through the copyingapparatus of this invention for projection copying frame by frame mayconsist of two motion picture step by step move ments coupled togethermechanically, as by gear- 1. In a copying device for ridged lenticularfilm,

an original ridged lenticular motion picture film and a sensitive copyridged lenticular motion picture film. both said films having the ridgesat an angle of approximately 45 degrees to the corresponding edges ofthe films, a translucent screen,

means to project on one side of said screen from said original film aseries of images in color, means to rephotograph from the opposite sideof said screen said images on said copy film frame by frame to producejuxtaposed linear color records on said copy film. and means to pass thefilm strips ridges at an acute angle to one edge of the film' strip, amotion picture camera for photographing said images on ridged lenticularcopy film having ridges identical with those of the original film, andmeans in the optical path between said films for producing a reversal ofthe image recorded on the copy film with respect to the picture on theoriginal film about one only of two coordinate axes lying in the planesof the films, one of which axes is parallel to the edges of said films.

HERBERT E. IVES.

